Selectively printing rotary duplicator

ABSTRACT

A rotary printing roller holds thereon a printing form having a plurality of circumferentially spaced printing sections. A counter roller cooperates with the printing roller, and one of the two rollers is movable to and from a printing position closely proximal to and defining with the other roller a printing line. A cam arrangement is provided for moving the movable roller to its printing position and maintaining it in the same for selected different portions of the time required for one revolution of the printing roller, so that the number of printing sections passing through the printing line is a function of the selected time portion. Signalling lamps are provided which are energized to indicate the printing sections which have been selected for printing.

United States Patent 11 1 Ritzerteld 1 1 Apr. 1, 1975 [54] LECTIVE PRrNTmG ROTARY 3.530.793 9/1910 Ritzerfeld 101/91 3.714.393 2/1973 Cole 101/228 DUPLlCATOR [76] Inventor: Gerhard Ritzerteld, Schorlemer Allee 14. 1000 Berlin 33. Germany [22] Filed: Apr. 18, 1973 1211 Appl. No.: 352,299

[30] Foreign Application Priority Data Apr. 20. 1972 Germany 2219940 [52] 11.5. CI. 101/91, 101/132 [511 int. Cl B411 47/46 [58] Field of Search l01/91.132,132.5

[56] References Cited UNITED STATES PATENTS 2.787.212 4/1957 Delplanque 101/132.5 2.843.039 7/1958 Ritzerfeld et a1. 101/132.5 3.090.287 5/1963 Ritzerfeld et a1. 101/91 X 3.109.355 11/1963 Ritzerfeld et 211. 101/132 3.245.364 4/1966 Ritzcrfeld et a1. 101/91 3.283.706 11/1966 101/91 3.420.163 1/1969 Ritzerfeld 101/91 Primary ExaminerEdgar S. Burr Assistant E.ran1iner-William Pieprz Attorney, Agent. or Firm--Michael S. Striker [57] ABSTRACT A rotary printing roller holds thereon a printing form having a plurality of circumferentially spaced printing sections. A counter roller cooperates with the printing roller. and one of the two rollers is movable to and from a printing position closely proximal to and defin ing with the other roller a printing line. A cam in rangement is provided for moving the movable roller to its printing position and maintaining it in the same for selected different portions of the time required for one revolution of the printing roller, so that the number of printing sections passing through the printing line is a function of the selected time portion. Signalling lamps are provided which are energized to indicate the printing sections which have been selected for printing.

8 Claims. 9 Drawing Figures SELECTIVELY PRINTING ROTARY DUPLICATOR BACKGROUND OF THE INVENTION The present invention relates generally to a rotary duplicator, and more particularly to a selectively printing rotary duplicator.

Selectively printing rotary duplicators are capable of printing individual lines, groups of lines or the entire contents of a printing form, depending upon which mode of operation is selected. Such machines are already known from the prior art, for instance from my prior US. Pat. No. 2,967,477 which teaches how the length of the printed section of a printing form can be varied, and U.S. Pat. No. 3,077,829 which discloses a selectively printing rotary duplicator. Such duplicators are used to print copy sheets. cards, webs or the like and are highly versatile in their application.

However, it has been found that further improvements in this field are desirable in order to increase the versatility of such apparatus still further, and also to increase the ease and reliability of operation thereof.

SUMMARY OF THE INVENTION It is, accordingly a general object of the present invention to provide a selectively printing rotary duplicator which incorporates such further improvements.

More particularly it is an object of the present invention to provide a selectively printing rotary duplicator which permits the sequential printing of printing sections of any desired size, which size may be varied at will.

Another object of the invention is to provide such an improved selectively printing rotary duplicator in which the printing sections whose selection for printing has been made, are indicated on a signalling device, for instance a device producing visually observable signals.

Another object of the invention is to provide such a selectively printing rotary duplicator which during the printing operation carries out an automatic cancellation of the selection of the printing section that has just been printed.

An additional object of the invention is to provide such a selectively printing rotary duplicator wherein, as the cancellation of the previously printed printing section is effected, the apparatus is automatically set for the beginning of the next section to be printed in accordance with the previously made selection.

In keeping with these objects, and with others which will become apparent hereafter, one feature of the invention resides in a selectively printing rotary duplicator which, briefly stated, includes a combination comprising a rotary printing roller having holding means for holding on the printing roller a printing form provided with a plurality of circumferentially spaced printing sections. A counter roller cooperates with the printing roller, and one of these rollers is movable to and from a printing position closely proximal to and defining with the other roller a printing line. Operating means is provided for effecting movement of the one roller to and from the printing position. Adjustable selecting means is associated with the operating means for moving the one roller to the printing position and maintaining it in the same for selected different portions of the time required for one revolution of the printing roller, so that the number of printing sections passing through the printing line is a function of the selected time portion. Signalling means provides signals indicative of the printing sections selected for printing, and actuating means is associated with the signalling means and the selecting means for actuating the former in response to printing of printing sections selected with the latter.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectioned somewhat diagrammatic side-elevational view of an apparatus according to the present invention, with portions omitted for the sake of clarity;

FIG. 2 is a fragmentary section taken on line A-B of FIG. 4;

FIG. 3 is a view similar to FIG. 2 but taken on line C-D of FIG. 4;

FIG. 4 is a horizontal section, looking down, through the portions of the embodiment which are shown in FIGS. 2 and 3;

FIG. 5 is a section taken on line G-H of FIG. 1',

FIG. 6 is an end view as seen in the direction of the arrow VI of FIG. 7;

FIG. 7 is a horizontal section, looking down, through FIG. 6;

FIG. 8 is a front view of a detail of the illustrated embodiment; and

FIG. 9 is a simplified wiring diagram concerning a detail of a control arrangement in the illustrated embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus according to the present invention has several functional units which will be discussed separately. Firstly, the control mechanism for adjusting the cams controlling the printing operation is illustrated in FIGS. 1, 2, 3, 4 and 5. The cam control of a rotary printing machine is basically already known, for instance from my prior US. Pat. No. 3,238,868 to which further reference may be had if desired.

Insofar as the present embodiment is concerned it will be seen that a printing roller 5 is mounted for rotation on a shaft 4. It is provided with non-illustrated but well-known means for retaining on the circumference of the printing roller 5 a printing form 27, that is a master carrying a plurality of printing lines or printing sections which are to be printed onto copy sheets. A cam shaft 6 is provided which is turned in synchronism with the shaft 4 via transmission gears I, 2 and 3. Mounted on the cam shaft 6 and retained thereon against rotation relative to the cam shaft 6 by means of the woodruff keys 7 and 8, are two gears 9 and 10, respectively. Thus, these gears rotate as the cam shaft 6 rotates.

A pawl 11 is mounted on the gear 9, and a similar pawl 16 is mounted on the gear 10. These pawls are of course pivotable in the usual manner and it will be seen that pawl 11 transmits motion resulting from rotation of the gear 9 to the gear 13, whereas pawl 16 similarly transmits motion of the gear 10 to the gear 18. Two housings l9 and 20 are provided, which are screwthreadedly connected with the gears 13 and 18, respectively. A coil spring 21 is accommodated in the housing 19 and a similar coil spring 22 is accommodated in the housing 20, each being connected with its opposite ends to the shaft 6 and the respective housing. A gear 23 provided with a cam 29 is threadedly fixed to the housing 19, and a similar gear 24 provided with a cam 28 is threadedly connected with the housing 20. The diagrammatically illustrated gear transmission 25 (see FIG. 1) serves to tension the springs 21 and 22 via the gears 23 and 24, respectively, the transmission 25 being turned by a non-illustrated drive which in turn is coupled with and uncoupled from the gear transmission 25 by a similarly non-illustrated and conventional electromagnetic coupling. The transmission and its operation are known per se from British Pat. No. 1,086,783.

If it is assumed, for the sake of explanation, that the arrangement is so set that it will normally and always print the first printing line of a plurality of lines or sections on the printing form 27 (although it can also be so set that it will normally not print any line, so that all lines must be selected), and that it is desired to print (in addition to the first line) the fourth, fifth, sixth and seventh lines of the printing form 27, then the pawl actuators l2 and 17 are moved three times in the direction of the arrow M (FIG. 2) and N (FIG. 3), respectively. This can be done for instance by means of plungers of non-illustrated electromagnets which push against the pawl actuators l2 and 17, respectively, in response to energization of switches connected with the electromagnets in question. Of course, other means besides electromagnets, for instance appropriate arms or the like, could be used for this purpose. In any case, this movement of the pawl actuators 12 and 17 causes the associated pawls 11 and 16 to sequentially disengage three circumferentially spaced teeth of the respective gears 13 and 18. This means that under the urging of the respective springs 21 and 22 the spring housings 19 and (which are tumable independently of one another) are now turned until the earns 29 and 28 associated with them are set for causing printing of the fourth printing line of the printing form 27. Thus, the apparatus is now ready to print automatically the first line and thereupon the selected fourth line, which latter printing operation will be initiated by the just-selected portion of the cam 28. Since it is desired to also print the fifth, sixth and seventh line, of which the latter is the last one to be printed, the electromagnet or other means associated with the pawl actuator 12 is now operated three more times, causing the pawl actuator 12 to become displaced again in direction of the arrow M (FIG. 2) and to permit the associated pawl 11 to disengage three additional circumferentially successive teeth of the gear 13. The spring housing 19 is therefore turned further by the spring 21, and with it the cam 29 until the latter reaches a circumferential position wherein its circumferential cam track portion will cause printing of the seventh line on the printing form 27. The direction of turning movement of the cams 28 and 29 is indicated by the arrow K (FIG. 1), and the combined overlapping circumferential cam track portions of the cams 28 and 29 will together cause the desired printing of the thus selected fourth through seventh lines.

With the cams 28 and 29 set in this manner, and if the cam 28 moves in rotation and in contact with the roller 37 of the cam follower 38, while the cam 29 moves in rotation and in contact with the roller 44 of the cam follower 45 (see FIG. 5), then the cam followers 38 and are pivoted in the direction of the arrow P (see FIG. 1) about the shaft 39 on which they are mounted for such movements. In so doing they similarly displace the control arm 40 in the direction of the arrow P, because the control arm 40 is also pivotably mounted on the shaft 39. The control arm 40 is connected with a fur ther control arm 60 which is pivotably mounted on a shaft 41. Also mounted pivotably on the shaft 41 is an arm which carries at its end remote from the shaft 41 a counter pressure roller 43 so that the latter is rotatable in parallelism with the shaft 4 on which the printing roller 5 rotates. The free end of the control arm has pivoted to it a link 42 the other end of which is pivoted to a further arm 56, and in turn the free end of the arm 56 is pivoted on the same shaft which carries the counter pressure roller 43. Thus, a pivoting of the control arm 60 about its shaft 41, initi ated by the pivoting of the control arm 40 in the direction of the arrow P, causes the link 42 to be displaced in the direction of the arrow R (FIG. 1) and thereby to pivot the counterpressure roller 43 against the periphery of the printing roller 5. A non-illustrated switch is operated, activating the electromagnet 26 (FIG. 2) to thereby move the cam 32 to its activating position S shown in phantom lines in FIG. 3, via the linkage members 30 and 31.

The apparatus is now in position for printing, in addition to the automatically printed first line of the printing form 27, the just-selected fourth, fifth, sixth and seventh lines of the printing form 27. For purposes of printing of these lines the printing roller 5 with the printing form 27 will perform one revolution, in synchronism with the cams 28 and 29.

The apparatus according to the present invention provides for an automatic cancellation of that printing line or printing section which has just been printed. Thus, if for instance printing line 4 has been printed the setting for this line is automatically cancelled. For this purpose the apparatus is provided with a roller 33 (see FIG. 4) which is so arranged that it is in the path of movement of the cam 32 when the latter is in the position S. An uncoupling member 34 is fixedly connected with the roller 33 and during the printing operation causes pressure upon the pawl 16 in a sense disengaging the latter from the gear 18. The thus released spring 22 causes the gear 18 to rotate and moves the surface 35a of an abutment 35 which is fixedly connected with the gear 18, against the surface 360 of an abutment 36 which is fixedly connected with the gear 13. A nonillustrated conventional roller can be provided which is operated by the electromagnet 26 in order to once again move the pawl actuator 17 once in the direction M, so that the next-following line, that is in the example being discussed the eighth printing line of the printing form 27, will automatically be set for printing. In other words, the first and eighth line will be printed in each and every case insofar as the example is concerned, whereas the fourth through seventh lines have been selected at will. If, following the printing of the eighth printing line, it is desired to have additional lines of the printing form 27 printed, then these must again be selected in the manner described above with respect to lines four to seven;

It is, of course, sometimes desired that the selected lines, such as the lines four to seven, be printed not once but repetitively, for instance on successive copy sheets. If that is desired then the switch which energizes the electromagnet 26 must be switched off. That being the case, and due to the effect of the linkage members 30 and 31, the cam 32 will return from the position S to its rest position and will thus not come in contact with the roller 33. This means that the connection between the pawl 16 and the gear 18 remains unchanged and is not dissolved, so that the selected lines four to seven of the example will be printed again during the next revolution of the printing roller 5.

The cancellation of the selected lines is effected, as discussed above, via the electromagnet 26, the linkage members 30, 31 and the cam 32, when the selected lines have been printed for the required number of times. This causes the surfaces 35a and 36a of the abutments 35, 36 to move into engagement.

When the printing operation during each revolution of the printing roller 5 is completed, the cam 29 is turned via the gear 23 that can be coupled to the aforementioned nonillustrated drive by means of a nonillustrated electromagnetic coupling. This causes the abutments 35 and 36 which thus act as blocking means to move into engagement and to turn the cam 28 back to the starting position, that is to the position in which automatic printing of the first printing line of the printing form 27 will take place during the next-following revolution of the printing roller 5. This arrangement therefore constitutes displacing means for the cams 28 and 29.

Coming now to FIGS. 6, 7 and 8, the electrical scanning and indication of the printing lines or printing sections to be printed will be described. As is illustrated in these Figures, gear 24 drives gear 46 (see FIG. 7) which in turn synchronously drives the cam plate 47 which is fixedly mounted on the shaft 48. When the cam 28 has moved to starting position, that is to the position in which the first of the selected printing lines of printing form 27 will be printed (in the above example it will be line 4), then the synchronous drive has moved the cam plate 47 with its contact portion 47a into engagement with the electrical contact 49. The cam plate is turned synchronously with the position of the cam disk 29 which selects the last of the selected lines to be printed, in the example the line 7. This movement is effected via a gear 23 and sleeve gear 51, the latter surrounding with its sleeve portion the shaft 48 as shown in FIG. 7. In so doing the contact portion 50a has moved to the electrical contact 52. Now, the contacts 49, S3, 54 and 52 are closed and via a non-illustrated conventional source of electrical energy they energize the signalling bulbs 55, 56, 57 and 58 in the arrangement shown in FIG. 8. This indicates optically that the printing lines four, five, six and seven have been selected for selective printing.

When the selection of a line is subsequently cancelled, then the cam plates 47 and 50 turn further as outlined earlier, and are then only overlapped with respect to the contact 59, that is the automatic printing of line 8 of the printing form 27 is now set for the next rotation of the printing roller. Of course. one or more lines can now again be selected for additional printing.

Referring to FIGS. 7 and 9, the cancellation of the selective-printing setting of the cam disks 28 and 29 is described, up to the desired head, that is the head portion of the printing form which is to be printed on every copy sheet. When the printing roller 5 is in its rest position, contact 75 (see FIG. 9) is closed. The printing of the head is known per se and can for instance be effected via the switch 72 (causing printing of one printing line) or via the switch 73 or the switch 74, causing printing of two or three printing lines, respectively. In any case, the respective contact is closed. If switch 71 is manually operated, then current flows through the circuit 75, 72, 61, 71 and the electromagnetic coupling 70 which starts to turn the gears 23 and 24 as described earlier. These gears effect rotation of the gears 46 and 51 and the contact arm 62 on gear 46 opens switch 61, so that the electromagnetic coupling 70 no longer receives current. At this time the cam 28 is in such a position that its starting portion is behind the first head printing line. In the next rotation of the printing roller the two-line or even a three-line head can be selected by switching on the switches 73 or 74. in this case the circuit to the electromagnetic coupling 70 is closed via the switches 75, 73, 63, 71 (for a two-line head) or the switches 75, 74, 65, 71 (for a three-line head). The contact arms 64 and 66 are so mounted on the sleeve gear 51 in circumferential direction thereof, that their spacing corresponds to the printing line distance and so that the contacts 63 and 65 will be switched off upon printing of the head printing line 2 or head printing line 3. Following these head printing lines the desired selected lines in the example the lines 4, 5, 6 and 7 can now be selected and subsequently be printed together with the number of lines making up the head, that is the single head printing line or the dual or triple head printing lines.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a selectively printing rotary duplicator, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In a selectively printing rotary duplicator having a drive for rotating a printing roller, a combination comprising a rotary printing roller including holding means for holding on said printing roller a printing form having a plurality of circumferentially spaced printing sections; a counter roller cooperating with said printing roller, one of said rollers being movable to and from a printing position closely proximal to and defining with the other roller a printing line; operating means for effecting movement of said one roller to and from said printing position; adjustable selecting means associated with said operating means for moving said one roller to said printing position and maintaining it in the same for selected different portions of the time required for one revolution of said printing roller, so that the number of printing sections passing through said printing line is a function of the selected time portion, said selecting means comprising at least two coaxial cam disks having circumferential cam track portions operative for engaging said operating means and moving said one roller to said printing position; signalling means for providing signals indicative of the printing sections selected for printing; actuating means associated with said signalling means and said selecting means for actuating the former in response to printing selections made with the latter, said actuating means comprising a pair of rotatable cam plates adapted to each be turned synchronously with one of said cam disks, said cam plates having actuating portions, and a stationary unit comprising a plurality of electrical contacts connected with said signalling means and arranged circularly about said cam plates so as to be operated by engagement with re spective ones of said actuating portions; and drive means for selectively effecting independent and joint movement of said cam disks about the common axis thereof, said drive means including first gears fixedly connected with the respective cam disks and each driv' ing a second gear, and said second gears each serving to drive one of said cam plates in synchronism with a respective one of said cam disks.

2. A combination as defined in claim 1, said printing roller being mounted for rotation about a first axis, said cam disks being turnable about a second axis paralleling said first axis, and said cam plates being turnable about a third axis also paralleling said first axis.

3. A combination as defined in claim 1 said drive means comprising displacing means for effecting circumferential displacement of said cam disks relative to one another during part of ajoint revolution performed by said cam disks.

4. A combination as defined in claim 3; and further comprising blocking means for blocking said cam disks against turning movement relative to one another upon completion of said circumferential displacement.

5. A combination as defined in claim 3, wherein said cam disks turn in one direction during joint revolution thereof; and wherein said displacing means comprises electromagnetic coupling means actuatable for effecting turning of one of said cam disks in an opposite di rection. and cancelling means turnable with the respective cam disks for deactivating said electromagnetic coupling means when said one cam disk reaches a predetermined circumferentially displaced position relative to the other cam disk.

6. In a selectively printing rotary duplicator having a drive for rotating a printing roller, a combination comprising a rotary printing roller including holding means for holding on said printing roller a printing form hav' ing a plurality of circumferentially spaced printing sections; a counter roller cooperating with said printing roller, one of said rollers being movable to and from a printing position closely proximal to and defining with the other roller a printing line; operating means for ef fecting movement of said one roller to and from said printing position; adjustable selecting means associated with said operating means for moving said one roller to said printing position and maintaining it in the same for selected different portions of the time required for one revolution of said printing roller, so that the number of printing sections passing through said printing line is a function of the selected time portion, said selecting means comprising at least two coaxial cam disks having circumferential cam track portions operative for engaging said operating means and moving said one roller to said printing position; signalling means for providing signals indicative of the printing sections selected for printing; actuating means including a pair of rotatable cam plates associated with said signalling means and said selecting means for actuating the former in response to printing selections made with the latter; and drive means for selectively effecting independent and joint movement of said cam disks about the common axis thereof, said drive means including displacing means for effecting circumferential displacement of said cam disks relative to one another during part of a joint revolution performed by said cam disks, and said drive means further including first gears each fixedly with one of said cam disks and each driving a second gear which serves in turn to drive one of said cam plates in synchronism with the respective cam disk.

7. A combination as defined in claim 6; and further comprising blocking means for blocking said cam disks against turning movement relative to one another upon completion of said circumferential displacement.

8. A combination as defined in claim 6, wherein said cam disks turn in one direction during joint revolution thereof; and wherein said displacing means comprises electromagnetic coupling means actuatable for effecting turning of one of said cam disks in an opposite direction, and cancelling means turnable with the respective cam disks for deactivating said electromagnetic coupling means when said one cam disk reaches a predetermined circumferentially displaced position relative to the other cam disk. 

1. In a selectively printing rotary duplicator having a drive for rotating a printing roller, a combination comprising a rotary printing roller including holding means for holding on said printing roller a printing form having a plurality of circumferentially spaced printing sections; a counter roller cooperating with said printing roller, one of said rollers being movable to and from a printing position closely proximal to and defining with the other roller a printing line; operating means for effecting movement of said one roller to and from said printing position; adjustable selecting means associated with said operating means for moving said one roller to said printing position and maintaining it in the same for selected different portions of the time required for one revolution of said printing roller, so that the number of printing sections passing through said printing line is a function of the selected time portion, said selecting means comprising at least two coaxial cam disks having circumferential cam track portions operative for engaging said operating means and moving said one roller to said printing position; signalling means for providing signals indicative of the printing sections selected for printing; actuating means associated with said signalling means and said selecting means for actuating the former in response to printing selections made with the latter, said actuating means comprising a pair of rotatable cam plates adapted to each be turned synchronously with one of said cam disks, said cam plates having actuating portions, and a stationary unit comprising a plurality of electrical contacts connected with said signalling means and arranged circularly about said cam plates so as to be operated by engagement with respective ones of said actuating portions; and drive means for selectively effecting independent and joint movement of said cam disks about the common axis thereof, said drive means including first gears fixedly connected with the respective cam disks and each driving a second gear, and said second gears each serving to drive one of said cam plates in synchronism with a respective one of said cam disks.
 2. A combination as defined in claim 1, said printing roller being mounted for rotation about a first axis, said cam disks being turnable about a second axis paralleling said first axis, and said cam plates being turnable about a third axis alsO paralleling said first axis.
 3. A combination as defined in claim 1 said drive means comprising displacing means for effecting circumferential displacement of said cam disks relative to one another during part of a joint revolution performed by said cam disks.
 4. A combination as defined in claim 3; and further comprising blocking means for blocking said cam disks against turning movement relative to one another upon completion of said circumferential displacement.
 5. A combination as defined in claim 3, wherein said cam disks turn in one direction during joint revolution thereof; and wherein said displacing means comprises electromagnetic coupling means actuatable for effecting turning of one of said cam disks in an opposite direction, and cancelling means turnable with the respective cam disks for deactivating said electromagnetic coupling means when said one cam disk reaches a predetermined circumferentially displaced position relative to the other cam disk.
 6. In a selectively printing rotary duplicator having a drive for rotating a printing roller, a combination comprising a rotary printing roller including holding means for holding on said printing roller a printing form having a plurality of circumferentially spaced printing sections; a counter roller cooperating with said printing roller, one of said rollers being movable to and from a printing position closely proximal to and defining with the other roller a printing line; operating means for effecting movement of said one roller to and from said printing position; adjustable selecting means associated with said operating means for moving said one roller to said printing position and maintaining it in the same for selected different portions of the time required for one revolution of said printing roller, so that the number of printing sections passing through said printing line is a function of the selected time portion, said selecting means comprising at least two coaxial cam disks having circumferential cam track portions operative for engaging said operating means and moving said one roller to said printing position; signalling means for providing signals indicative of the printing sections selected for printing; actuating means including a pair of rotatable cam plates associated with said signalling means and said selecting means for actuating the former in response to printing selections made with the latter; and drive means for selectively effecting independent and joint movement of said cam disks about the common axis thereof, said drive means including displacing means for effecting circumferential displacement of said cam disks relative to one another during part of a joint revolution performed by said cam disks, and said drive means further including first gears each fixedly with one of said cam disks and each driving a second gear which serves in turn to drive one of said cam plates in synchronism with the respective cam disk.
 7. A combination as defined in claim 6; and further comprising blocking means for blocking said cam disks against turning movement relative to one another upon completion of said circumferential displacement.
 8. A combination as defined in claim 6, wherein said cam disks turn in one direction during joint revolution thereof; and wherein said displacing means comprises electromagnetic coupling means actuatable for effecting turning of one of said cam disks in an opposite direction, and cancelling means turnable with the respective cam disks for deactivating said electromagnetic coupling means when said one cam disk reaches a predetermined circumferentially displaced position relative to the other cam disk. 